Art of casting metals



L M. PERRY. ART 0F CASTINGMETALS.

FILED NOV. I6. 1922.

FIG..

Mar. 6v, 1923.

Fis. 2;.

' I I J0a/ I Patented ar. 6, 1923e JAMES M. PERRY, F DETRUIT, MICHIGAN,ASSIGNOR 0F TWO-THIRDS TO HIMSELF AND ONE-THIRD TO HORACE G. SEITZ,

OF DETROIT, MICHIGAN.

ART OF CASTING METALS.

Application led November 16, 1922.

To aZZ whom t may concern.'

Be it knoWn that I, JAMES M. PERRY, a

citizen of the United States, residing at Derapid to troit, in thecounty of Wayne and Sta-te of Michigan, have invented certain new anduseful Improvements in the Art of Casting Metals, of Which the followingis a specification.

This invention relates to improvements in the art of casting metals, andpertains more particularly to methods designed to eliminate the presenceof imperfections in the casting, such, for instance, as are usuallycaused by the presence of air or gas bubbles or holes produced by sa-ndparticles Where the casting is made in sand molds.

One of the major difficulties in producing castings is that caused bythe rapid chilling or solidification of the molten metal., especiallyWhere the castings are of the thin-Walled type. In order that thecasting may be of proper character it is essential that the metal bepoured With sufficient rapidity that there be no opportunity for oneportion-the part into which the initial metal first flows to its finalposition, for instance-to reach solidification before the remainder ofthe metal has been poured; this to prevent the formation of specificzonal conditions Within the casting. Where metal molds are employed7 itmay be possible to resist this action by heating the Walls of the mold,but Where the mold is of sand, this aid cannot be had and the pouring ofthe metal must be sufficiently prevent conditions of this kindappearing.

Rapid pouring of the metal raises the problem of the escape of air orgas to prevent the formation of holes in the castingrendering thecasting more or less porous. This is due to the fact that the flow ofthe metal may imprison bubbles, and these must escape by passingupwardly; and where solidifcation begins before a bubble has reached thetop, it remains imprisoned within the casting and provides animperfection therein in the form of a hole which may or may not extendto the surface-it is generally found beneath the surface of the casting.And where the casting is had With sand molds, the additional problemarises through the dislodgment of sand particles which pass into themolten metal and must, to be eliminated, rise to the top surface of thecasting; should the particle fail to reach.

Serial N0. 601,351.

the top, it forms an imperfection which, if exposed by machining, etc.,leaves a hole in the casting.

As will `be understood, the difficulty in both cases arises by reason ofthe time element that is introduced through the conditions of thebeginning of solidification of the molten metal; Whatever that length oftime may be, the air or gas bubbles or the sand particles or both mustreach the neck or other waste portion of the casting before thesolidiication begins if imperfections of this kind are to be prevented.Vhere the metal remains fluid or molten suiiiciently long, these sourcesof imperfections Will reach the waste Zone of the casting-the dificultycomes under conditions Where the castings are of such character as toset up the beginning of solidification before the time required for thenatural movement of the sources of imperfections hasended.

The problem is one that pertains generally to the art'of casting, andbecomes of especial importance in connection with comparativelythin-Walled structures in which the length of the casting in t-he`vertical direction during pouring is such as to prevent a materialdistance for the imperfection sources to travel in reaching the Wastezone, a condition that tends to produce the gas bubble imperfection dueto the necessity for comparatively rapid pouring of the metal. Castingsof this kind are required in many arts and have many differentcross-sectional shapes, a condition that the present invention isdesigned to meet.

F or the purpose of illustrating the characteristics of the invention,Without, however, limiting the same to the particular form and purposeindicated, I disclose herein the application of the invention to theproduction of castings used for the purpose of a blank from Which pistonrings are formed, the general method for producing such rings being theformation of 'a cast cylinder of the proper metal-cast in sandmolds--the cylinder being of proper diameter, AWith comparatively thinWalls, and generally of a supply length of about eight inches with theupper end in the form of a neck or other type of Waste zone; this latterforms a part of the casting and is removed and cast aside during theproduction of the rings.

Due to the thin Walls and the vertical length of the casting,imperfections of the type mentioned are generally found in thesecastings, the number and location of the imperfections varying withdifferent castings, it being an extreme exception to find a cylinderfree from all imperfections having these sources. The effect of thepresence of these and the effect produced in the cost of piston ringconstruction can be under stood from a brief reference to theconstruction of the rings from the cylindrical casting or blank.

After casting, the blank is machined to the proper dimensions and cut toproduce the proper Width of ring. ln many forms of rings thecross-section is of a type that does not include parallel Wallsextending normal to the axis of the blank, and in these cases themachining and production of one ring serves to produce a portion ofanother ring. The result is that it becomes necessary-to obtain themaximum number of rings from the blank, to machine the latter as if itwere Wholly free from imperfections, after vvhich the rings areinspected, and those found imperfect are cast aside as not usable; sincethe rings are of narrow Width, the dividing of the blank serves to`practically expose-at some point at leastthe presence of the hole ordepression that stamps the ring as a discard.

,From this it is possible to sce that the presence of the imperfectionsinvolves considerably more than the simple loss of the material found inthe immediate zone of the imperfection Whether or not the ring be aperfect ring or a discard, the machining and other production cost isthe saine in each case-Whatever be the cost of the perfect ring, thesame cost applies to the discard. Not only is this excess losspresent-due to the necessity for completing the discard the same as ifit be a perfect ring-another ad-l ditional cost is found in the`necessity for inspecting all rings in order to separate the perfect andthe discard rings. So that the perfect rings must carry the entiremanufacturingcost of both perfect and wasted `rings, additional to thecost of inspection.

And ivith a fairly high Waste ring` factor present(` the production costof the piston ring department of an auto plant or of the plantmanufacturing rines alone, requires a comparatively high selling' pricein order lto cover the losses produced by the presence of theimperfections in the initial casting.

The general purpose of the present inven` tion 1s to eliminate this lossby eliminating` 'its source-the imperfections in the casting. `And toproduce this result I employ the general principles of adhesion. Forinstance, ifa. suitable structure be moved through the molten metal inthe direction lof natural flow of the imperfection sources,

these latter Will pass to and move with. the

Lair/gaia' structure through the molten metal during movement of thestructure. So that if the structure be located at the bottom of the moldand then be drawnthrough the molten metal toward the Waste neck of thecasting, the bubbles or the sand particles Will be carried from theservice portion of the casting and moved into the Waste portion, if thestructure move'into the latter; if the structure be Withdrawn theimperfection sources Will be brought to the surface.

Obviously, the structure employed for re. moving the imperfectionsources would have dimensions such as to be of less thickness than thethickness of the casting Wall on the plane of action of the structure.For instance, if the casting be of cylinder form and comparativelythin-ivalled-the piston ring supply casting, for examplethe structuremay be in the form of a ring of vvire of suitable material and gage andof a diametersuch as to be approximate the medial diameter of thecylinder, so that, if accurately positioned, the ring would besubstantially symmetrically positioned Within the cavity of the mold andthus pass through the molten metal approximately central of the Wallthickness. Accuracy to an extreme degree is not, however, required inthe move ment of the structure through the centre or the Wall,approximate accuracy being sufficient, it being preferred that thestructure move Within the molten mass rather than in contact with themold Wall, since such latter 'movement might tend to increase theintroduction of the sand particles.

Une or more wire elements may be secured to the structure, theseextending vertically and of a length to project above the mold cavity,these serving as handles to move the structure through. the metal; andfor convenience the ends of these handles may be bent laterally orotherwise shaped to permit ready manipulation of the structure.

The movement of the structure may be had upon completion of thepouring-if the Wall thickness is such as to-delay the beginning ofsolidification sufficiently to permit the pouring and the movement ofthe structure to be completed. However, a preferred Way of use is tolocate the structure at 'the bottoml of the mold cavity and after aportion of the metal has been poured, begin the movement of thestructure upwardly-in the direction of natural movement oftheimperfectionV sources-and continue such movement during the remainder ofthe pouring movementq the active portion of the structure alwaysremaining below the level of the poured metal; the structure thusfollows up the level of the poured metal, and after pouring has beenended, the movement is continued until the active part of the structureyhas passed into the Waste Zone or entirely removed. If permitted toremain llt) agir/,sir

in the waste zone of the casting, it becomes embedded t ierein throughthe solidnication action and can be cast aside with the waste' neclnbeing serviceable as a handle for the casting while so. embedded.

lt is to be understood, of course, the the movement of the eliminatingstructure talres place while the metal is molten so that free movementof the structure is had and movement of the imperfection sources cantaire place. Surface cooling probably does not affect the action as longas tie sources are free to move with the freely moving eliminatingstructure. lf the metal be in its fluid or molten state, however, t Aemovement of the structure will cause the imperfection sources to pass toit and move onward with it as long as the structure is embedded withinthe molten metal, doing this through the activity of the generalconditions of adhesion-and possibly some of the characteristics ofadsorption-the shifting' of the molten metal by the passage of thestructure through it aiding in this result, the metal closing in behindthe advancing structure and forming a casting` from which theimperfection sources have been removed.

By the elimination of the source of the imperfections the castingbecomes wholly serviceable, so that wastage in rings is prevented, andit becomes practically unnecessary to provide inspection of rings, wherethe methods are employed in the production of piston-ring-supplycastings.

To these and other ends, therefore, the nature of which will be readilyunderstood as the invention is hereinafter disclosed, said inventionconsists in the methods of castingl hereinafter more fully described,illustrated in the accompanying' drawings, and more particularly pointedout in the appended claims.

In the accompanying drawings, in which similar reference charactersindicate similar parts in each of the views,-

Figure l is a vertical central sectional view of a mold for producingthe blank cylinder which forms the supply for the production of pistonrings, showing elin'iination structure in initial position.

Fig. 2 is a similar view of the upper end of the mold, showing' theelimination structure raised to the waste Zone and frozen into thematerial of the zone.

Fig. 3 is a. perspective view of one form of eliminati-on structure thatmay be employed.

Fig. fl is a similar view of a different formation of the eliminationstructure.

Fig. 5 is a sectional view of a portion of a, mold showing another wayin which the invention may be practiced.

As heretofore pointed out, l have shown the invention as employed inconnection with the casting of the cylinder that forms the supply sourcefor the production of piston thev rings, a form that presents thecharacteristics of a circular tube. lt is obvious that the casting` tobe formed may be of other cross-sectional contour, so that it isunnecessary to show other forms, that shown being suflicientlyillustrative to enable a. proper understanding of the characteristics ofthe invention to be had.

ln the drawing, the mold-shown as a sand mold for purpose ofillustration-is indicated at l0, and the core at ll, these beingarranged to form a cylindrical cavity l1 with an enlarged neclz7 11a,the latter ceiving the material of the waste Zone of the casting. As themold is sh-own as having the top of the cavity closed, it will beunderstood that the usual pouring gate will be employed; obviously,however, the mold may nave its top open. As will be understood, thelength of the cavity ll will be that required to produce. the desired,length of supply cylinder-the general standard beine about eightinches, while the thickness or the wall of the cylinder casting will besuch :is to provide the casting has been machined.

Because of the comparatively thin wall of the cylinder', it will bereadily understood that the inner and outer surfaces of the poured metalcool rapidly, so that the casting is of a rapid solidificationcharacteristic. rlhis, as previously pointed out, sets up the conditionsof imprisoned gas bubbles and of sand particles, solidilicatimi takingplace before these can pass to the top waste zone. through the naturalaction. It is to meet this condition, and aid in the elimination throughproducing a rapid movement of an elimination structure orinstrumentality through the molten metal in the general direction of thenatural movement of the imperfection sources, thus carrying' these tothe waste zone before solidilication taires place.

The elimination instrumentality may be of any suitable form andmaterial, two simple forms-applicable for use in the particular mold ofthe drawingsbeing illustrated as examples of what may be used for thepurpose. Each of these sets up the conditions of a portion that has thegeneral contour of a cross-section of the suiviply portion of thecasting, and a portion or portion that may serve as handles to thisportion.

Since the contour of the cavity shown in the drawing circular. theportion l2 of the instrumentality has this contour. either by being of asuhstantiall).v continuous ring contour, as in F 3, or by the use of twosegmental portions lZa adapted to be placed in position to set up thering-shaped contour, as in Fig. 1l. ln either case. the cross-section ofthe material of the ring or segment is sufciently less than the width ofthe cavity as to ensure that it can travel through the molproper sizering when the vthe ring portion, kshown as a pair ten metal withoutdisturbing the surface of Tthe poured :metal at the sides of thepositioned metal, the purpose being to prevent cient length to projectfrom the top of the mold, this being simply illustrative of variousforms and positions of handles that may be employed. The handles areshown as oppositely-dis} 3osed and may, if desired, be bent laterally orgiven other formations enternal of the mold to enable the workman tomore readily manipulate the instrumentality.

The instrumentality may be formed of wire of suitable material. lt maybe of the material of which the casting is made so tha-t should there beany tendency to be melted, it will not affect the material of thecasting; preferably it is of material of sufficient heat resistingquality to maintain itself during the short perior it remains within thecylinder portion of the mold.

The handles may `be secured to the ringshaped portion in suitablemanner, as by welding, but preferably by being integral with it; and forpurposes of ready production, but one handle may be provided, although lprefer to use at least two, since this permits of more accurate raisingof the ring through the molten metal. Possibly a simpler and lessexpensive formation is illustrated in Fig. 4,'in which theinstrumentality is of two parts, each having a pair of handles, theassembly ofthe two parts placing two handles-one from each part-side byside. Obviously, other ways or forms may be employed for producing theinstru-` mentality, as, for instance, one of the handles of the segmentof Fig. i may be omitted, and the free end of the segment united tothehandle of the other segment. And it will be understood that, inpracticing the invention, the double member instrumentality would beoperated in the same manner as the single member structure of Fig. 3,both members being moved upwardly concury rently.

lThe instrumentality may follow the level of the exposed surface duringpouring, or the movement of the instrumentality may be delayed until thepouring has been coinpleted, this depending more or less upon the timethat elapses between pouring of the metal and its solidiiication to suchan extent as to prevent the desired action of the instruof moving thering.

mentality. The particular conditions present in the production of thecasting will determine which course to pursue. Where the action is thatof following up the topsurface of the poured metal, it is necessary thatthe ring portion remain below the surface.

As heretofore pointed out, the movement of the instrumentality throughthe molten metal sets up the conditions of the principles of adhesion,the air ortgas bubbles, or

the sand particles, moving to the ring'part and rising with the latter,thus moving at a different speed from the natural speed of travel ofthese imperfection` sources in a casting of this type, theinstrumentality thus aiding the elimination of these sources by changingthe speed of travel from the natural speed to that of theinstrumentality itself. So that, if the speed of travel of theinstrumentality be sufficiently rapid as to permit it to reach the wastezone of the casting before actual solidiication is set up, theimperfection sources will be carried to this zone and the supply portionof the casting will be freed of these imperfections.

The instrumentality may be permitted to freeze within the waste zone ofthe casting, and thus serve as a handle for the casting; this isespecially the case where the mold carries a top, the latter thencarrying suitable openings through which the handles extend and aremoved. vWhere an open top mold is employed, the instrumentality may beentirely withdrawn, leaving .the imperfection sources within the wastezone; but inasmuch as the instrumentality will possibly become uselessafter performing the service, there is probably no advantage to begained through entirely withdrawing it.

As will be understood, the instrumentality can be positioned within thecavity at the time the mold is produced, remaining there until thepouring of the metal takes place..

lf desired, thej surface of theinstrumentality may be provided with acoating; for instance a coating of clay may be applied and bakedthereon, thus rendering the metal of the instrumentality less likely tobe affected by the heat of the molten metal.

As will be understood, the portion of the instrumentality that is mainlyeffective in practicingthe invention is the ring-like portion shown inthe drawing-that portion that corresponds in contour to thecross-section of the castingg'the handle portion is designed moreparticularly for the purpose Because of this fact it is possible to varythe particular method of providing the ring movements, an additional waybeing shown in Fig. 5, in which the ring is free from connection withhandles and is moved by members l5 that are movable through the lowerwall of the mold, these members resting Hush with the bottom of thecavity, and being moved upwardllO ly to raise the ring into the Wasteportion of the casting and then quickly Withdrawn to the initialposition to maintain the bottom of the cavity closed. Members l5 may beseparate Wires, or may form a part of an instrumentality fabricated topermit of concurrent movement-cross-head 15a illustrating a simplearrangement for the purpose. This Way of practicing the invention may beadvantageous under certain conditions, but necessitates that themovement of the ring be completed While the metal remains sufficientlyfluid to permit Withdrawal of the members l5 before solidification andin order that the metal of the casting may flow into the space leftvacant by the members.

As Will be understood, the method herein set forth is more particularlyadapted for service under conditions Where the casting is of acomparatively thin-Walled type, thus permitting the action of theinstrumentality to become effective Without materially disturbing themolten metal itself as the instrumentality moves through it, a resultpermitted by the use of an instrumentality of comparatively smallcross-sectional dimensions and at' the same time'be effective in settingup the conditions of adhesion reaching substantially to the surfaceofthe casting. Where the casting is of thick Walls or is of `solidformation, as with billets, etc., for instance, the eifective zone ofadhesion, can only reach the surface by the use of an instrumentality ofrelatively large cross-sectional dimensions, the result being that thereis a material disturbance of the molten metal by the instrumentalityduring the Withdravval activity, due to the necessity of the metal abovethe instrumentality to pass around the latter, an action that couldreadily produce gas bubble formations as Well as dislodge sand particlesfrom the mold, leaving the casting With the imperfections presenttherein. Hence, in referring to thin- Walled structures it is theintention to place in somewhat contrasting effect, the type ofstructures referred to herein and those which may be of the billet orthe ingot type, or of structures of solid formation having relativelylargevdimensions, such latter structures having dimensions such as torender it difficult, if not impracticable, to eliminate imperfections bythe methods herein described, due to the fact that the largecrosssection would require at best a very complicated instrumentality,the use of which Would set up other difficulties such as to make the useof the method less advantageous.

While I have herein shown and described several .Ways in Which thegeneral invention may be practiced, as Well as diiferent forms ofinstrumentalities that may be employed therein, it Will be readilyunderstood that `and be carried with the these are simply illustrativeand that varia-- tions and modifications in the methods and in theinstrumentalities employed may be found desirable or essential inmeeting the various exigences of use; for instance, the mold may be ofother' materials than sanda metal mold, for example. I therefore desireto be understood as reserving the right to so vary or modify the methodspracticed and the instrumentalities employed in such practice, as may befound desirable or necessary, in so far as such variations ormodifications may fall Within the spirit and scope of the invention asexpressed in the accompanying claims, when broadly construed.

Having thus described my invention, what l claim as new is:

l. ln the art of casting metal for thc production of castings ofgenerally uniform cross-section in the direction of length of thecasting, and wherein the casting is of a comparatively thin-Walled type,the method of eliminating imperfections ofthe bubble or hole typetherefrom, Which method consists in moving the imperfection sources fromthe poured metal to a Waste Zone by increasing the normal speed oftravel of the sources in the direction of natural movement thereof to anextent sufficient to carry the sources to such zone prior tosolidilication of the metal.

2. In the art of casting metal for the production of castings ofgenerally uniform cross-section in the direction of length of thecasting, and wherein the casting is of a comparatively thin-Walled type,the method of eliminating imperfections of the bubble or hole typetherefrom, which method consists in moving the imperfection sources fromthe poured metal to a Waste zone by moving an instrumentality bodilythrough the poured metal in the general direction of natural movement ofthe imperfection sources and intermediate and spaced from the faces ofthe casting and throughout the source Zone of the casting, the movementof the instrumentality being at sufficient speed as to complete itsmovement to the Waste zone prior to metal solidification to therebycause the imperfection sources to pass to instrumentality by adhesion.

3. In the art 0f casting metal for the production of castings ofgenerally uniform cross-section in the direction of length of thecasting, and wherein the casting is of a comparatively thin-Walled type,the method of eliminating imperfections of the bubble or hole typethereform, which method consists in moving the imperfection sources fromthe poured met-al to a Waste zone by locating an instrumentality of thegeneral configuration of a cross-section of the casting and of lessdimensions than the thickness of the casting titl llO

`molten metal in the direction of natural movement of the imperfectionsources to cause such sourcesto pass to and be carriedl by the body intothe Waste zone at speed greater than the Inatural speed of travel oiLlthe sources.

4. ln the art of producing castings of circular contour and adapted to'form the supply for the production of piston rings, andfivherein thecasting` includes a Waste zone located at the upper end of the casting`when being; produced, the method of eliminating imperfections of thebubble or hole type -trom the casting, Which method consists in locatingan instrumentality at the bottom of the mold and between and spaced fromthe opposing Walls of the mold cavity with the instrumentality contourof a form to correspond generally t a cross-section of the casting.ring-supply portion, and then movingthe instrumentality through thepoured metal in they direction of natural movement of the imperfectionsources and toward and into the Waste zone prior to metalsolidiiication, the movement o'l the instrumentality causing' theimperfection sources to pass to and be carried with the instrumentalityby adhesion activity into the refinar? waste zone at greaterspeed thanthe natural i speed of vtravel of such sourcesthroughy the molten metal.

5. ln the art of casting metal for the production or castings ofgenerally uniform cross-section in the direction of lengthrof thecasting, means operative by `its movement through the molten metal .ofthe casting in the direction otnaturalimovemento1 imperfection sourcesto a Waste Zone to ehminate imperfections of the bubble or holeandspaced from such Walls, and means.-`

operative to movethe instrumentality bodily through the poured metal tocarry the instrumentality into the-Waste zone in advance of metalsolidification.

6.. Means formoving the instrumentalityas in claim 5 characterised inthat theinstrumentality-moving means isadapted* to cause instrumentalitymovement in a direction substantially parallel to the; Walls of 'themold cavity to retain the instrumentality Within the molten metal andspacedv :trom

the opposing surfaces thereof.

In testimony whereof I have hereunto aixed my signature.

JAMES M. PERRY.

